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Dark matter particles may be heavyweights after all

DESPITE making up 80 per cent of the universe, dark matter is maddeningly elusive. Now it is giving up a few secrets – although not its full identity.

Dark matter provides the gravity that stops galaxies from flying apart, but interacts so weakly with ordinary matter that it is unclear what it is. Now two separate analyses of gamma rays in space, some of which formed in dark-matter collisions, give a clue. They suggest that if dark matter is made up of particles, as leading theories suggest, these must be at least 44 times as heavy as protons. “This is the …